For hygiene pants, in the form of diaper pants for children and adults and in the form of sanitary towel pants, very high demands are placed on fit and comfort. The hygiene pants must have such elasticity in the transverse direction that they are easy to take off and put on by the user, by a parent or by a care provider. There is also a requirement that they should be soft and textile-like. The hygiene pants, in particular for adult users, must be discrete and they should not be bulky, at least in the areas outside the actual absorption unit. Since they are disposable products, the cost aspect is very important. For cost reasons, the material layers included must be as thin as possible. At the same time, quality and strength requirements must be fulfilled. The hygiene pants, such as diaper pants, must of course resist wear during use. Hygiene pants are exposed to considerable stresses when being put on. The hygiene pants are stretched when they are being pulled over the users hips, and said weld seams are exposed to great stresses. Especially critical areas are the ends of the weld seams at the leg openings or the waist. A break in the weld starts in these critical areas.
In traditional diaper pants, the covers are made up of double nonwovens and of elastic threads lying between these. In the weld seams on this type of cover, there are no fewer than four layers of bonded nonwoven, which gives a sufficiently strong weld seam. The expression bonded nonwoven used here means a nonwoven in which the bonds have not been broken open or weakened in connection with the production of the cover.
Hygiene pants of the type mentioned at the outset have a cover in the form of an elastic laminate composed of an elastic film applied between two nonwoven layers. The weld seams on this type of elastic laminate are affected, in respect of the strength of the seams, by the structure and make-up of the laminate. One object of elastic covers in the form of an elastic film between two nonwoven layers is to give the cover optimal elastic properties at the same time as the fibers in these nonwoven layers give the cover a soft textile feel. The structure of the laminate should therefore be configured such that elastic stretching of the cover is not impeded by the nonwoven layers.
An example of elastic laminates of the type mentioned at the outset is described in WO 03/047488. This publication discloses an elastic laminate composed of an elastic film applied between two nonwoven layers. During production of the elastic laminate, these nonwoven layers have been connected to the film, after which the laminate has been stretched until the bonds in the nonwoven layer have been broken. The elasticity of the laminate is therefore made largely the same as the elasticity of the elastic film. An important disadvantage of this solution is that the weld seams have considerably less strength than the weld seams on said traditional diaper pants.
Other examples of elastic laminates of the type mentioned at the outset are described in the two PCT applications 2004/001004 and 2004/001005. In contrast to the production method according to WO 03/047488, the bonds of the at least one nonwoven layer have not been completely broken open and, instead, the layer has a certain residual strength. The PCT applications 2004/001004 and 2004/001005 describe solutions where elasticity has been combined with softness and with resistance to puncture. In these constructions too, the weld seams are weaker than in said traditional diaper pants.